ReText

ReText is simple open source text editor that supports
Markdown and reStructuredText markup languages. ReText gives users the
power to control all output
formatting. Markdown and reST are WYSIWYM markup languages, so if you
save a document as plain text, anyone will be able to see how it has
been formatted. ReText also has support for tabs.

ReText is written in Python using PyQt libraries.

ReText supports text formatting and can save to
different file formats (PDF, HTML).